Forming method of Silicon epitaxial layer

PURPOSE: A method for forming a silicon epitaxial layer is provided to form an excellent epitaxial layer on a silicon substrate under 700 °C by using a new pre-cleaning process. CONSTITUTION: A dopant region(130) is formed on the predetermined portion of a silicon substrate(110) by implanting predetermined ions into the semiconductor substrate using a material pattern(120) as a mask. The surface of the silicon substrate is cleaned by using mixed plasma, wherein the mixed plasma is made of etching gas containing F, H2, or D2. A silicon epitaxial layer(140) is formed on the surface of the silicon substrate. Preferably, the doping concentration for the silicon substrate is in the range of 10 exponential 18-21 atom/cm3. Preferably, the plasma cleaning process is carried out at the pressure of 1 mTorr -1 Torr.